Telephone set



Jan, 141-, T1936. H. QBERGFELL 2,27,549

TELEPHONE SET Filed July 18, 1932 4 Sheets-Sheet 1 Fig.1

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TELEPHONE SET Filed July 18, 1932 4 Sheets-Sheet 2 IMPULSE SPRINGS AND MECHA N/SM Jam 14, 1936., H F QBERGFELL 2,,@27,54

TELEPHONE SET Filed July 18, 1952 4 Sheets-Sheet 3 -Im r.enZcrr- Harm F UEFU Jan. M, 1936. H. F. OBERGFELL 2,27,4@

TELEPHONE SET Filed July 18, 1932 4 Sheets-Sheet '4 Inventor HEPEFI' F EH E IEH Patented Jan. 14, 1936 UNITED STATES PATENT OFFICE TELEPHONE SET Application July 18, 1932, Serial No. 623,049

3 Claims.

The present invention relates in general to telephone sets in particular to types of telephone sets in which all of the talking and signalling instrumentalities are included in a single box; in which the transmitter and receiver are incorporated in a handset unit; and in Which an automatic calling device is provided for establishing connections with other telephones.

The principal object of the invention is to design a telephone of this type which is arranged so that all of the parts are compact and easily accessible, pr sent a pleasing appearance, and are light in weight and economical to manufacture.

A further object of the invention is to design a telephone set in which all of the parts are completely enclosed, including contacts and circuit closers, so that the telephone is entirely gastight and flame-proof.

In accordan e with the above object, a particular feature of the invention resides in a switchhcok-operating arrangement in which the switchhook contacts are enclosed in an evacuated vessel or glass tube so that they are not exposed to the atmosphere, and are actuated externally through a suitable lever arrangement by means of the removal and replacement of the handset.

A further feature of the invention resides in providing the automatic calling device with an extended bearing and shaft for actuating the impulse springs so that when they are actuated and create sparking, escaping gases will be prevented from being ignited.

A further feature of the invention resides in providing a spring clip which engages the handle of the handset unit to prevent it from moving or swaying and unintentionally actuating the hookswitch contacts.

Another feature is concerned with a removable base plate and cover for supporting the telephone in which all of the wires and terminals are supported so that the complete telephone may be easily removed and replaced upon its support without completely dismantling it.

A particular utility for a telephone set constructed according to the invention is for communication purposes between the different points in an aircraft which uses inflammable gas for its lifting power, so that special precautions must be taken to prevent stray, accidental, or other sparks caused by the operation of contact points or other portions of a telephone set, from igniting the gas. Similarly, in all other aircraft special precautions must be taken to prevent the ignition, by electrically operated apparatus such as a telephone set, of the gaseous fumes or vapors generated or accumulated by the gasoline and oil used in propelling the airship.

Another use for telephones according to the invention is in steamor battleships, underground mines, buildings or factories, or any other place where special precautions are necessary to insure that explosive gaseous vapors will not become ignited and cause explosions.

The above particular features and others not specifically mentioned are illustrated in the accompanying drawings and pointed out more specifically in the description.

In the drawings, Fig. 1 illustrates a plan view on a reduced scale of a telephone set according to the invention; Fig. 2 shows a fu1l-size view with some of the apparatus shown in section along the line 2-2 of Fig. 1; Fig. 3 illustrates a full front view of the switchhook-operating mechanism and the means for supporting it; Fig. 4 is a front view on a reduced scale of the cover or supporting plate for the telephone; Fig. 5 is an extended view of certain parts of the mechanism of the calling device; Fig. 6 is a view of a modified portion of a telephone set which may be included in the telephone of Fig. 1; and Fig. 7 illustrates schematically the circuit arrangement employed in the telephone.

Referring now more particularly to Figs. 1 and 2, the telephone set comprises essentially a casing 5 of rectangular shape, preferably made of aluminum in order to conserve weight and which contains all of the necessary apparatus used in operating the instrument. An aluminum cover or base plate 6, shown more clearly in Fig. 4, is attached to a suitable supporting surface and supports the casing 5 by means of bolts and nuts 1 on the bottom side and 8 on the top. A pair of audible signalling horns I0 and H are supported on opposite sides of the casing 5 by means ofbolts 46. The operating units for the horns may comprise any well-known type of receiver having a diaphragm, over the periphery of which the horns are threaded directly. A visual lamp I2 comprising preferably a neon lamp is screwed to a socket or base l3 which in turn is attached to the top side of the aluminum casing 5 by means of a bolt and nut 14 on opposite sides of the socket. A metal guard l5 fastened by screws to the top of the casing 5 protects the lamp I2 from damage.

Referring now more particularly to Figs. 2 and 3, an aluminum supporting bracket 20 having a number of extensions is arranged on the front side of the casing 5. The oppositely disposed extensions 23 and 24 secure the bracket 26 to the casing by means of the screws 22. A handsetsupporting bracket 25 is mounted on top of the bracket 20 and by means of the bolts 2| on each side this member together with the bracket 20 is secured to the front side of the casing 5. The bracket 26 also has a pair of oppositely disposed and forwardly projecting members 26 and 21 which form a support for the switchhook contact and operating members, as will hereinafter be pointed out, and to the ends of which by means of a pair of screws 2828 threaded into the members the aluminum enclosing cover 29 is secured. This cover 29 separately encloses the switchhook contact-operating mechanism and other parts as will hereinafter be apparent.

The telephone handset member is of wellknown construction comprising a handle 30 having a. transmitter unit 3| incorporated in one end and in the opposite end a receiver unit 32. This handset unit mas be of any preferred construction, the details of which are not pertinent to the invention. A bent spring wire clip 33, shown more clearly in Figs. 1 and 2, is secured by means of bolts 34 to the cover 29 and is arranged to resiliently grasp each side of the handle portion 30 of the handset. The purpose of this spring clip 33 is to maintain the handset 30 in a steady upright position and always resting normally on the switch contact-operating member 50 so that the constant swaying or rough motion and movement of the vessel or body upon which the telephone instrument is mounted will not inadvertently actuate the switchhook contacts. This spring member 33, while preventing accidental swaying or unintentional displacement of the handset 30, is not of suflicient grasping strength to prevent the ordinary removal and replacement of the handset when in actual use for talking purposes.

A talking condenser 35, together with a signalling condenser 36 of smaller size, is supported between the brackets 23 and 24 by means of a bolt 31 on each end, and a small resistance coil 38 adjacent the condensers is bolted onto the casing 5.

As shown more clearly in Figs. 2 and 4, an insulating block 4| is suitably mounted on the cover or base plate 6 and has in turn secured thereto a pair of terminals 42 to which the signalling conductors are attached together with a pair of terminals 43 to which the line or talking conductors are secured. Spring clips on each of the terminals 43 serve as mounting points for the terminals of the lightning arrester 44, the other end of which is snapped into a spring clip secured directly to the cover plate 6 which thereby serves as a grounding plate. A number of openings 45 in the back of the face plate or cover 6 permit access and egress of the telephone cables and wires for the telephone set. A number of holes 46 on each corner of the cover serve as a. means for supporting the telephone by means of bolts to its supporting surface. The openings 47 in each side of the casing 5 permits entrance of the connecting wires for the actuating unit of the horns.

The switchhook-contact-operating mechanism, constituting a feature of applicants invention, is shown clearly in Fig. 3 and comprises a plunger or push-button member 50 which is normally pressed inward in the casing 29 by means of the handle portion 30 of the handset and when the handset is removed it projects outward. The plunger 50 is journaled in a sleeve which is secured to a supporting bracket 5| which in turn is clamped at each end by means of clamps 52 to the ends of the bracket members 26 and 21 through the medium of screws 53. A pair of spring members 54 secured to the bracket member 5| engages a pair of rollers 55 which are in turn rotatably mounted on the U-shaped member 56 which is pivoted between the ends of the bracket 5|. The U-shaped member 56 has an extension to which the cam member 51 is attached by means of screws. A further extension of the U-shaped member 56 projects from the opposite side and is attached pivotally to one end of the reciprocating plunger 50. The arrangement and action of the aforesaid parts is such that upon the inward movement of the button 50 the extension of the U-shaped member 56 is pushed downward, rotating the member 56 about its pivot, so that the rollers 55 engage the ends of the springs 54, storing tension into them. The opposite extension of the U-shaped member 56 likewise moves the cam member 51 forward or" to the right as seen in Fig 2. Releasing the pressure on the button 56 reverses the action and restores the cam member 51, under the action of the tension stored in springs 54, to its normal position. For a more detailed description and disclosure of a switchhook-operating arrangement similar to that just described, reference may be had to Patent No. 1,738,919, issued December 10, 1929, to the same inventor.

The pair of contacts 58 which are utilized to open and close the telephone circuit by the removal and replacement of the handset upon the cradle member 25 are enclosed in a glass tube or vessel 69 which is highly evacuated and entirely sealed, so that the arcing or sparking caused by the opening and closing of the contacts 58 is considerably reduced, thereby preventing burning of the contacts and at the same time also preventing any sparks, which may be generated, from gaining admission to the surrounding atmosphere outside the vessel. The connecting wires are completely sealed in the glass vessel 66 and extend out at the right-hand side of the unit. A pair of metal straps 6| spaced apart encircle the glass vessel 60 and securely hold it in position by means of a pair of screws threaded into the side of the bracket 5|. In order to actuate the contacts 58, the glass stem 62 is formed in the vessel and it has one end attached to a corrugated portion formed in the glass and extending to the lefthand end of the tube 60 in such a manner that movement of the rod 62 opens and closes the contacts 58 through the medium of the elasticity inherent in the glass. The cam member 5'! of the switch-hook-operating mechanism normally bears on one side of the tube 62 and moves it downward, thereby opening the contacts 58 when the handset is in normal position. When, however, the handset is removed from the hook member 25 the pressure of the cam member 51 is removed from the stem 62 and the stem assumes its normal position, as shown. This movement is accelerated by means of the leaf spring 63 bearing mechanism of the calling device is contained Within two separate circular casings H and I4,

I preferably made of aluminum. The casing I4 is attached to the rear side of the casing ll by means of a series of screws 15 around its periphery. The joint between the two casings H and M is such that it is practically gasor air-tight. A cover plate 79 attached by means of a series of screws "ll to the casing 14 effectively closes the rear end of the casings containing the mechanism. A circular plate 18 forms a support for the internal operating mechanism and contact springs of the calling device mechanism, and is attached to the front side of the casing 14 by means of a series of screws 19. A relatively long hollow pin 80 is threaded into one side of the casing 14 and the connecting wires for the contact springs of the calling device are passed through this pin. A suitable amount of plastic insulating compound is forced into the opening provided in pin 89 and around and between the connecting wires so that an air-tight connection is made. It is seen that the casings II and 14 are completely air-tight.

Before proceeding further with a description of the internal operating mechanism of the calling device, reference may be had at this point to Patent No. 1,642,822, granted September 20, 1927 to the same inventor, for an automatic calling device which, except for a certain particular part which will hereinafter be pointed out, is of exactly the same construction as the instant case. All of the parts and mechanisms shown in Fig. 3 of the aforesaid patent are contained within the dotted area of the casing 14, but for the sake of clearness have not beenshown therein.

The number plate of the calling device is secured to the casing H on its front side by means of clips 96 and screws. The circular protruding portion 84 formed out of the center of the casing H has a bushing or bearing 99 extending through it. The bushing 99 has a head one end resting on the front side of the easing 7|, while a nut 92 threaded onto the bushing 99 securely clamps the bearing to the projecting portion 84 of the casing H. A rotatable steel shaft or pin 9| extends through the bearing with a very close fit but loose enough so that it is easily rotatable in it. Threaded t0 the end of the rotatable shaft 9| is a screw 8! having a relatively large head. The screw 81 clamps the calling device finger plate 10 and a special key washer 88 directly on top of the end of the bearing 9|. As seen more clearly in Fig. 5 and the aforesaid calling device patent, the finger hole dial has an openingwith parallel sides which fit closely over the raised portion I03 also having opposite parallel sides on the top of washer 8B. The under side of the washer 88 has a slot 89 cut in it which fits over a square-cut portion I09 formed in the end of the shaft 9 I. The foregoing arrangement is such that the screw 81 holds the finger plate keyed securely on top of the special washer 88 and the special washer 88 in turn is clamped securely and keyed to the top of the shaft 9|. The fiber washer I92 on the righthand side of the shaft 9| and washer HM on the left-hand end serve as thrust bearings. From the foregoing arrangement and assembly of parts it is clearly seen that rotation of the finger-hole plate 19 permits the rotation of the shaft 9| in the same direction.

The plate has a bearing pin 96 formed integral with it which rotates inside of the bearing 98 fastened to plate 18. The plate 95 carries a pawl which engages ratchet teeth formed on the right side of the rotatable gear wheel 91, while the left-hand side of the gear wheel 91 contains a series of gear teeth which, as shown in the patent, rotate a small pinion gear which drives the cam wheel for making and breaking the impulse springs of the calling device. The gear wheel 91 is rotatable on the outside of the bearing 98. The front side of the plate 95 has a projecting piece NJ! with parallel sides formed in it which fits into engagement with slot 94 cut in the head of the shaft 9|. The left-hand end of the rotating pin 96 has a slot with which one end of a coil spring I90 is in engagement, while the other end of the spring makes engagement with a projection on the supporting plate 18. A pair of arms |0| clamped on the left-hand end of the bearing pin 96 serves to make and break the shunt springs of the calling device.

The foregoing arrangement of parts is such that clockwise rotation of the finger plate 10 rotates the shaft 9| in the bearing 99, and the slotted left-hand end 94 of the bearing pin 9| turns the projection l0! of the plate 95, thereby rotating the pawl mounted on the plate 95 across the teeth of the ratchet or gear wheel 91. At the same time the bearing pin 96 is rotated to store tension in the spring I09. When the finger plate 19 is released, the bearing pins 96 and 9| are rotated back to normal position under the tension stored in spring I00. The gear wheel 97 is thereby rotated to turn the small pinion gear (not shown) with which it is in engagement, and thereby make and break the impulse contacts. At the same time the shunt springs are operated. The whole mechanism, as shown in the aforesaid patent, is under control of a suitable governor device.

It will be noted that the bearing surfaces between the shaft 9| and bushing 99 is somewhat greater than would ordinarily be necessary. The reason for this relatively large bearing surface for the rotating mechanism of the calling device is that, as the impulse springs are operated as well as the shunt springs, sparks are generated and arcing occurs across the contact points. This may well be a serious menace and a dangerous occurrence when the telephone is used in the vicinity of explosive gases, as has been pointed out. A number of openings on the mounting plate 18 which are punched out of it and are used to support various parts of the mechanism permit communication between the chambers formed by the casings II and I4. Should any explosive gases accumulate in these casings and a flame or explosion result therefrom, this will be prevented from reaching the outside atmosphere due to the fact that the relatively long bearing surface between the shaft 9| and bearing 99 is in existence. Similarly, no spark can extend far enough through the bearing surfaces to ignite gaseous fumes in the near vicinity of the tele phone. This forms an effective seal for the purposestated.

Since the casing 5 and enclosure casing 29 as well as the cover or supporting plate 6 are all made of sheet metal which in this instance is aluminum, the telephone set may easily be grounded to dissipate any stray currents which may exist or accumulate in the apparatus, thereby preventing further danger from this source. In addition, this arrangement prevents interference with nearby radio sets by completely shielding all the telephone apparatus.

Referring now to Fig. 6, in certain instances it may be desirable to provide one of the existing telephones with separate signalling means whereby a special code may be sounded throughout a telephone system in which a number of telephones according to the invention are installed. To this end an extension casing I I0 may be attached to the bottom side of the casing 5 by means of the screws 1. A pair of push buttons I H and H2 are mounted in the face of the casing H0 together with suitable indicia above them. On the rear side of the casing H0 circuit-closing or contactmaking devices are provided for each of the pushbuttons H0 and H2. These contacts may be of the same construction and operation as the glass vacuum vessel used in connection with the switchhook-operating button 50, so that the sparking of the contacts cannot reach the outside atmosphere but are confined within the glass tube. A similar mechanical arrangement connects the buttons Ill and H2 with the vessels to actuate the contacts within them.

Fig. 7 discloses a schematic circuit diagram of the telephone set. It will be noted that the signalling conductors are attached to the terminals 42 on the block ll in a separate circuit from the talking conductors. Current is passed over them to actuate the horns l0 and II and the signal lamp 12, the condenser 35 being used to reduce the load on both horns. The lightning arrester M is connected in circuit across the talking conductors directly at the terminals 43. The talking circuit extends over one of the talking conductors through the switchhook contacts 58 enclosed in the vacuum glass tube 60, which contacts are maintained normally open due to the weight of the handset 35 resting on the push-button 50. The connection then extends through the impulse springs I05 of the calling device 10, which impulse springs are shunted by the condenser 36 and the resistance 38 which serve to reduce the sparking across the contacts of the impulse springs I05. The circuit then extends in series through the transmitter and receiver units of the handset 30 and then outward over the other talking conductor. During the time that the impulse calling device 10 is actuated and the dial is rotating back to its normal position, the impulse springs I05 are being rapidly opened and closed. At this time, the shunt springs I06 short circuit the transmitter and receiver of the handset 30 in order to reduce the impedance of these units while dialling is taking place.

What is claimed is:

1. In a telephone set, a handset, means for supporting said handset on said telephone, an operating button operated by the removal and replacement of said handset on said telephone set, an evacuated vessel having a projecting stem extending therefrom, switchhook contacts completely sealed in said vessel, and operating mechanism connecting said stem on said vessel with said operating button for actuating said switchhook contacts, said mechanism including a cam face mounted to slide across said stem when the button is operated.

2. In a telephone set in which a support is pro- 3. In a telephone set having a handset unit supported upon it together with an operating member actuated by the removal and replacement of the handset unit on the telephone set, a sealed evacuated vessel having a stem, a cam member having one end connected to said operating member and the other end slidable across said stem for moving the same, a spring member engaging said stem for restoring it to normal after having been actuated by said cam member, and switchhook contact springs entirely sealed in said glass 40 vessel and operated by the movement of said stern.

HERBERT F. OBERGFELL. 

